Anyone else's sons obsessed with each other's willies and bums?

Just that really...my nearly six year old and 4.5 yr old have been pretty interested in their and each other's willies and bums for about a year now. Mainly kicks off in the bath and initially I ignored it, then my mums advice was to get them to lick other things like soap, the sponges, bath toys, (as opposed to each other's bottoms) and occasionally they don't do it, but I would say on the whole it is a fairly consistent theme. Before I know it, one will have his bum thrust in he the air and the other will be trying to lick it. Now, my dh and dm say this is normal. I am not so sure. Last night, the older one bit the younger ones bum leaving teeth marks and tonight when I was putting baby to bed, I came in to find the little one was chanting "I am going to lick your willy". Is this the usual anal / sexual phase of development as named by Piaget and Bowlby? How do I react? Am terrified my over reacting will cement this behaviour as something negative in their futures, but equally and worried that under reacting and ignoring it will lead to them 'experimenting' with each other on an increased basis. Or god forbid, other children! Any psychoanalysts, or developmental consultants opinions welcome!

My two boys of the same age behave similarly so don't panic (more fixation on willies than bottoms)!

However, I have said clearly and firmly that no one is to ever touch their willy/bottom and that they are therefore not to touch each other's. End of conversation and repeat ad infinitum.

Personally I would not read too much into it, however I am very keen for them to know that another person touching their willy/bottom is not acceptable and have said that if anyone does, they should tell me.

I have always told my two boys (4 & 8), that their willies are private and are to be kept private - seen by themselves only. The elder of the two now dresses in private, any silliness around the issue is strictly forbidden.

It's a bit extreme, but it seems to have nipped that kind of behaviour in the bud more or less.

When I tell them that licking/touching/sticking toes up each other's bums is not good behaviour, they just fall about laughing. I have tried a variety of punishments from being sent to bed without a story, smacked bottoms, a ban on tv the following day...but the message just isn't getting across that they can't touch each other's bums and that their own are private. I am genuinely worried they will take this behaviour outside the bathroom and extend it into every day life, like school or nursery. Also, are they going to suddenly get obsessed with their baby sisters foo foo? So far there are no signs of interest. Thank god.

This isn't sexual behaviour, it is normal child behaviour. There is no reason to stop it. They need to know the underwear rule to protect them from other people but they are not at risk from each other. I would tell them to not lick each other's willies and bums because that is where wee and poo comes from so isn't a good idea. If they ever did it anywhere but home, then I would deal with it then, but I wouldn't worry now.

My 3 and 8 year old son's occasionally bath together, sometimes they show interest in each other's bits, other times they don't say anything. My three year old often tells his big brother he has a stinky willy, sometimes the conversation turns a bit silly, but it doesn't last for long, generally my 8 year old prefers a bath alone now, as he's getting older and says he likes the peace and quiet. I think it's a good idea to let children know they should keep their hands to themselves, it also makes them aware that if someone didn't keep their hands to themselves, or touched them inappropriately, they know it's not right for another person to do that. Talking about each other's bits and touching themselves is perfectly normally, I guess it's just a matter of having boundaries like anything.